1. Field of the Invention
The present invention pertains to the art of cooking appliances and, more particularly, to cooking appliances employing electric heating element support brackets adapted for microwave applications which, in addition to supporting a heating element within an oven, act as both a ground and an RF shield.
2. Discussion of the Prior Art
The art of cooking is currently undergoing substantial change. No longer is it the norm to have a family member home all day to prepare meals. Today, more and more consumers must rush home from work to prepare meals for themselves or their families. Time is of the essence, with the luxury of spending time preparing meals rapidly becoming a thing of the past. In light of these time constraints, consumers are demanding cooking appliances that will cook a meal in less time than conventional ovens, without sacrificing the quality of the prepared food. In order to meet these demands, manufacturers are combining conventional cooking systems with the rapid cook advantages of microwave cooking systems.
Microwaves perform a cooking process by directing a microwave or RF energy field into an oven cavity. The RF energy field is in the form of a standing wave which reflects about the oven cavity and impinging upon a food item. As the RF energy fields impinge upon the food item, the energy fields are converted into heat through two mechanisms. The first or ionic is constituted by the linear acceleration of ions, generally in the form of salts, present within the food item. The second is the molecular excitation of polar molecules, primarily water, present within the food item.
When introducing microwave systems into conventional ovens, there are several considerations which must be addressed. For instance, metal components within the oven cavity must be grounded in order to prevent damage to the microwave components. Metal located in the oven cavity may potentially reflect a portion of the RF energy field back into the magnetron. The reflected RF energy is dissipated as heat within the magnetron which causes distortions in the energy field, as well as ultimately leading to total failure of the component. In order to substantially eliminate this problem, an RF energy shield is needed to protect the magnetron. One effective method of establishing a shield is to properly ground all metal components. In this manner, the metal components will not act in a manner similar to that of an antenna transmitting the RF energy back into the magnetron. This is particularly true in connection with the mounting of metal components with screw or other mechanical fasteners which can act as antennae for microwaves, with arcing being a potential problem.
In light of the above, a primary concern in conventional ovens having an electric heating element is the particular mounting and placement of the element within the oven. Placing the heating element in the oven cavity where it is exposed to microwave energy requires specific design considerations. Mechanical fasteners and support brackets used to secure the element to the oven can act as an antenna which focuses the RF energy and causes arcing within the oven. Continued arcing reduces the operational life of the magnetron, while also decreasing the overall efficiency of the appliance. Based on the above, there exists a need in the art of cooking for an electric heating element support bracket which can be arranged within the oven cavity. Particularly, there exists a need for a support bracket which serves as a ground for an electric heating element so as to provide an RF shield for preventing reflected microwave energy from damaging internal system components.